Neurons

neuron

A nerve cell that sends messages from the body to the brain and vice versa, enabling functions like breathing, talking, eating, and thinking.

interneuron

Neurons that make up most of the neurons in the body, regulate motor activity, carry sensory information, and assist with reflexes.

synapse

The small space between two neurons, necessary for communication when messages are passed from one neuron to another.

axon terminal

The structure at the end of an axon that releases neurotransmitters to convey signals across synapses.

synaptic vesicle

Holds neurotransmitters and releases them during synapse, triggered by calcium during exocytosis.

neurilemma

The plasma membrane that surrounds a Schwann cell covering the axon of a neuron, protecting peripheral nerve fibers.

action potential

The rapid sequence of changes in a cell's membrane potential, triggered by an electrical impulse traveling along the axon.

all-or-nothing principle

The principle stating that when a nerve fiber is stimulated, it will fire an impulse regardless of the stimulus strength.

gradient

The rate of change over a distance or time, such as concentration differences.

electrolyte

A substance that produces electricity when broken down into charged particles (ions) through movement.

passive transport

The movement of chemicals across a cell membrane from high to low concentration without energy usage.

active transport

The process of moving molecules or ions across a cell membrane from low to high concentration, requiring energy.

unipolar neuron

A type of neuron that conducts impulses toward and away from the cell body, typically a single process sensory neuron in PNS ganglia.

multipolar neuron

A neuron with one axon and many dendrites that transfers and integrates information, the most abundant type in humans.

soma

The part of a neuron that contains the nucleus and DNA, synthesizes macromolecules, and transports proteins through axons and dendrites.

axon

The part of a neuron that carries electrical impulses away from the cell body to other neurons.

dendrite

A branched extension of the cell body that carries messages from neurons into the cell body, receiving and processing synaptic signals.

node of ranvier

Gaps in myelinated neurons that help conduct nerve impulses, enriched with sodium and potassium ion channels.

myelination

The process of creating a myelin sheath around a nerve cell axon, composed of glial cells and lipids.

saltatory conduction

The transmission of nerve impulses down a myelinated axon from one node of ranvier to another.